1. Ubuntu Security Notices
  2. USN-4728-1

USN-4728-1: snapd vulnerability

Publication date

10 February 2021

Overview

An intended access restriction in snapd could be bypassed by container management snaps.

Releases

Packages

  • snapd - Daemon and tooling that enable snap packages

Details

Gilad Reti and Nimrod Stoler discovered that snapd did not correctly specify cgroup
delegation when generating systemd service units for various container
management snaps. This could allow a local attacker to escalate privileges
via access to arbitrary devices of the container host from within a
compromised or malicious container.

Gilad Reti and Nimrod Stoler discovered that snapd did not correctly specify cgroup
delegation when generating systemd service units for various container
management snaps. This could allow a local attacker to escalate privileges
via access to arbitrary devices of the container host from within a
compromised or malicious container.

Update instructions

In general, a standard system update will make all the necessary changes. On Ubuntu, snapd will automatically refresh itself to snapd 2.48.3 which is unaffected. Affected container management snaps will also automatically refresh which will restart containers and resolve this vulnerability.

Learn more about how to get the fixes.

The problem can be corrected by updating your system to the following package versions:

Ubuntu Release Package Version
20.10 groovy snapd –  2.48.3+20.10
20.04 focal snapd –  2.48.3+20.04
18.04 bionic snapd –  2.48.3+18.04
16.04 xenial snapd –  2.48.3

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References

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